"The driver of one of the trains was still unaccounted for and thought to be inside the wreckage, police spokesman Jean-Christophe Sauterel said.

" 'These are regional trains. The speeds are a little lower and even if one deeply regrets the likely loss of life of one person as well as five serious injuries, the situation could have been much more catastrophic,' he said.

"Switzerland's rail system is considered among the best and safest in the world. Accidents are rare, though three years ago the country's popular Glacier Express tourist train derailed in the Alps, killing one person and injuring 42."